Epidemiologic evaluation of inhaled nitric oxide use among neonates with gestational age less than 35 weeks

Retrospective study of preterm infants exposed to inhaled nitric oxide in Kaiser Permanente Southern California: morbidity, mortality and follow-up

OBJECTIVE

Describe characteristics of preterm infants exposed to inhaled nitric oxide (iNO) in Kaiser Permanente Southern California.

STUDY DESIGN

Case review of preterm infants <34-weeks exposed to iNO during 2010-2020 including respiratory and echocardiographic status, NICU course, and 12-month follow-up.

RESULTS

270 infants, 2.63% of births<34 weeks, (median, range: 26.1, 225/7-336/7 weeks gestation) were exposed to iNO. Median FiO2 at iNO initiation was 1.0 (IQR 0.94-1.0). Pulmonary hypertension (PH) was not associated with risk-adjusted 2 h oxygenation response or improved survival. Mortality to NICU discharge was 37.4%. Median cost of iNO was $7,695/patient. Discharged survivors experienced frequent rehospitalization (34.9%), use of supplemental oxygen, sildenafil, diuretics, bronchodilators, and steroids. Four infants had persistent PH. Five infants died after NICU discharge.

CONCLUSIONS

Preterm infants receiving iNO have high mortality and 1st year morbidity. As currently used, iNO may be an indicator of respiratory disease severity rather than mediator of improved outcomes.

The early use of inhaled nitric oxide in premature infants requiring respiratory support

Background: Earlier studies on the use of inhaled nitric oxide (iNO) for premature infants born at <34 weeks of gestation requiring respiratory support did not provide conclusive evidence of benefit. National guidelines generally discouraged the use in this population. More recent national guidelines endorsed the use of iNO in premature infants with hypoxic respiratory failure (HRF) associated with persistent pulmonary hypertension of the newborn (PPHN).Recent Studies: Two recently published observational studies evaluated the effect of administering iNO on oxygenation in the first week of life. These studies compared premature infants born at the gestational age (GA) of <34 weeks with HRF associated with PPHN to term and late preterm infants born at the GA of ≥34 weeks who received iNO. Both studies showed a similar effect of iNO on oxygenation in the two infant cohorts. The response rate in the premature infant cohort was 59% in the first study and 90% in the second. The mean response time was 9.2 h and 10.3 h, and the mean duration of therapy was 3.5 days and 8.2 days, respectively.Conclusion: The results of these studies support a trial of iNO in premature infants with persistent hypoxia despite optimum respiratory support. Obtaining a timely echocardiogram to exclude cardiac diseases and diagnose PPHN is logistically challenging for many clinicians, thus, a clinical diagnosis of PPHN might have to be made in these situations. Questions remain regarding the optimum dose of iNO and the duration of the initial iNO trial in these patients.KEY MESSAGESIn the most recently published studies, the improvement of oxygenation in iNO-treated infants born at <34 weeks of gestation with HRF and PPHN physiology was as effective as in infants born ≥34 weeks.These studies provide evidence supporting a trial of iNO in the subpopulation of premature infants with HRF associated with PPHN.

[Recent research on inhaled nitric oxide in preterm infants with a gestational age of <34 weeks]

Nitric oxide is a messenger molecule for vasodilation of vascular smooth muscle cells, and inhaled nitric oxide (iNO) can dilate pulmonary blood vessels and reduce pulmonary vascular resistance, thereby reducing pulmonary artery pressure, but with no influence on systemic circulation pressure. Guidelines in China and overseas recommend the use of iNO in full-term infants and late preterm infants, and it has been proved that it has a marked effect on persistent pulmonary hypertension and hypoxic respiratory failure in such infants. However, recent studies have shown that there is an increase in the off-label use of iNO in preterm infants with a gestational age of <34 weeks. This article reviews the research progress on the efficacy, safety, timing, dose, and withdrawal mode of iNO and its combination with vasoactive drugs in the treatment of preterm infants with a gestational age of <34 weeks in China and overseas, so as to provide a reference for clinical application.

Inhaled nitric oxide in premature infants for preventing bronchopulmonary dysplasia: a meta-analysis

BACKGROUND

The effectiveness of nitric oxide (NO) in reducing the risk of bronchopulmonary dysplasia (BPD) remains debatable. In this study, we performed a meta-analysis to guide clinical decision-making regarding the significance of inhaled NO (iNO) on the potential occurrence and outcomes of BPD in premature infants.

METHODS

Data from clinical randomized controlled trials (RCTs) published in PubMed, Embase, Cochrane Library, Wanfang, China National Knowledge Infrastructure (CNKI) and Chinese Scientific Journal Database VIP databases for premature infants were searched from inception to March 2022. Review Manager 5.3 statistical software was used for heterogeneity analysis.

RESULTS

Of the 905 studies retrieved, 11 RCTs met the screening criteria of this study. Our analysis showed that the iNO group was associated with a significantly lower incidence of BPD than the control group (relative risk [RR] = 0.91, 95% confidence interval (CI) 0.85-0.97, P = 0.006). We also observed no significant difference in the incidence of BPD between the two groups at the initial dose of 5 ppm (ppm) (P = 0.09) but those treated with 10 ppm iNO had a significantly lower incidence of BPD (RR = 0.90, 95%CI 0.81-0.99, P = 0.03). However, it should be noted that although the iNO group had an increased risk for necrotizing enterocolitis (NEC) (RR = 1.33, 95%CI 1.04-1.71, P = 0.03), cases treated with an initial dose of 10 ppm revealed no significant difference in the incidence of NEC compared with the control group (P = 0.41), while those treated with an initial dosage of 5 ppm of iNO had a significantly greater NEC rates than the control group (RR = 1.41, 95%CI 1.03-1.91, P = 0.03). Further, we observed no statistically significant differences in the incidence of in-hospital mortality, intraventricular hemorrhage (IVH) (Grade 3/4) or periventricular leukomalacia (PVL) and pulmonary hemorrhage (PH) between the two treatment groups.

CONCLUSIONS

This meta-analysis of RCTs showed that iNO at an initial dosage of 10 ppm seemed more effective in reducing the risk of BPD than conventional treatment and iNO at an initial dosage of 5 ppm in preterm infants at a gestational age of ≤34 weeks who required respiratory support. However, the incidence of in-hospital mortality and adverse events between the overall iNO group and Control were similar.

Controversies in neonatology: The efficacy of inhaled nitric oxide in preterm infants with persistent pulmonary hypertension

Introduction: There is limited and conflicting information in literature regarding use of inhaled nitric oxide (iNO) in preterm infants. In this study we examined the characteristics of preterm infants with persistent pulmonary hypertension (PHT) who responded and did not respond to iNO therapy . Material and Method: We retrospectively reviewed data of infants